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checkout: don't revert file on ambiguous tracking branches

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For easier understanding, here are the existing good scenarios:

  1) Have *no* file 'foo', *no* local branch 'foo' and a *single*
     remote branch 'foo'
  2) `git checkout foo` will create local branch foo, see [1]

  and

  1) Have *a* file 'foo', *no* local branch 'foo' and a *single*
     remote branch 'foo'
  2) `git checkout foo` will complain, see [3]

This patch prevents the following scenario:

  1) Have *a* file 'foo', *no* local branch 'foo' and *multiple*
     remote branches 'foo'
  2) `git checkout foo` will successfully... revert contents of
     file `foo`!

That is, adding another remote suddenly changes behavior significantly,
which is a surprise at best and could go unnoticed by user at worst.
Please see [3] which gives some real world complaints.

To my understanding, fix in [3] overlooked the case of multiple remotes,
and the whole behavior of falling back to reverting file was never
intended:

  [1] introduces the unexpected behavior. Before, there was fallback
  from not-a-ref to pathspec. This is reasonable fallback. After, there
  is another fallback from ambiguous-remote to pathspec. I understand
  that it was a copy&paste oversight.

  [2] noticed the unexpected behavior but chose to semi-document it
  instead of forbidding, because the goal of the patch series was
  focused on something else.

  [3] adds `die()` when there is ambiguity between branch and file. The
  case of multiple tracking branches is seemingly overlooked.

The new behavior: if there is no local branch and multiple remote
candidates, just die() and don't try reverting file whether it
exists (prevents surprise) or not (improves error message).

[1] Commit 70c9ac2f ("DWIM "git checkout frotz" to "git checkout -b frotz origin/frotz"" 2009-10-18)
    https://public-inbox.org/git/7vaazpxha4.fsf_-_@alter.siamese.dyndns.org/
[2] Commit ad8d5104 ("checkout: add advice for ambiguous "checkout <branch>"", 2018-06-05)
    https://public-inbox.org/git/20180502105452.17583-1-avarab@gmail.com/
[3] Commit be4908f1 ("checkout: disambiguate dwim tracking branches and local files", 2018-11-13)
    https://public-inbox.org/git/20181110120707.25846-1-pclouds@gmail.com/

Signed-off-by: Alexandr Miloslavskiy <alexandr.miloslavskiy@syntevo.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Alexandr Miloslavskiy 2019-12-30 18:38:13 +00:00 committed by Junio C Hamano
parent 2957709bd4
commit fa74180d08
2 changed files with 51 additions and 33 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

56
builtin/checkout.c
View file

@ -1115,10 +1115,10 @@ static void setup_new_branch_info_and_source_tree(
static const char *parse_remote_branch(const char *arg,
struct object_id *rev,
int could_be_checkout_paths,
int *dwim_remotes_matched)
int could_be_checkout_paths)
{
const char *remote = unique_tracking_name(arg, rev, dwim_remotes_matched);
int num_matches = 0;
const char *remote = unique_tracking_name(arg, rev, &num_matches);
if (remote && could_be_checkout_paths) {
die(_("'%s' could be both a local file and a tracking branch.\n"
@ -1126,6 +1126,22 @@ static const char *parse_remote_branch(const char *arg,
arg);
}
if (!remote && num_matches > 1) {
if (advice_checkout_ambiguous_remote_branch_name) {
advise(_("If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
"you can do so by fully qualifying the name with the --track option:\n"
"\n"
" git checkout --track origin/<name>\n"
"\n"
"If you'd like to always have checkouts of an ambiguous <name> prefer\n"
"one remote, e.g. the 'origin' remote, consider setting\n"
"checkout.defaultRemote=origin in your config."));
}
die(_("'%s' matched multiple (%d) remote tracking branches"),
arg, num_matches);
}
return remote;
}
@ -1133,8 +1149,7 @@ static int parse_branchname_arg(int argc, const char **argv,
int dwim_new_local_branch_ok,
struct branch_info *new_branch_info,
struct checkout_opts *opts,
struct object_id *rev,
int *dwim_remotes_matched)
struct object_id *rev)
{
const char **new_branch = &opts->new_branch;
int argcount = 0;
@ -1240,8 +1255,7 @@ static int parse_branchname_arg(int argc, const char **argv,
if (recover_with_dwim) {
const char *remote = parse_remote_branch(arg, rev,
could_be_checkout_paths,
dwim_remotes_matched);
could_be_checkout_paths);
if (remote) {
*new_branch = arg;
arg = remote;
@ -1505,7 +1519,6 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
const char * const usagestr[])
{
struct branch_info new_branch_info;
int dwim_remotes_matched = 0;
int parseopt_flags = 0;
memset(&new_branch_info, 0, sizeof(new_branch_info));
@ -1613,8 +1626,7 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
opts->track == BRANCH_TRACK_UNSPECIFIED &&
!opts->new_branch;
int n = parse_branchname_arg(argc, argv, dwim_ok,
&new_branch_info, opts, &rev,
&dwim_remotes_matched);
&new_branch_info, opts, &rev);
argv += n;
argc -= n;
} else if (!opts->accept_ref && opts->from_treeish) {
@ -1672,28 +1684,10 @@ static int checkout_main(int argc, const char **argv, const char *prefix,
}
UNLEAK(opts);
if (opts->patch_mode || opts->pathspec.nr) {
int ret = checkout_paths(opts, new_branch_info.name);
if (ret && dwim_remotes_matched > 1 &&
advice_checkout_ambiguous_remote_branch_name)
advise(_("'%s' matched more than one remote tracking branch.\n"
"We found %d remotes with a reference that matched. So we fell back\n"
"on trying to resolve the argument as a path, but failed there too!\n"
"\n"
"If you meant to check out a remote tracking branch on, e.g. 'origin',\n"
"you can do so by fully qualifying the name with the --track option:\n"
"\n"
" git checkout --track origin/<name>\n"
"\n"
"If you'd like to always have checkouts of an ambiguous <name> prefer\n"
"one remote, e.g. the 'origin' remote, consider setting\n"
"checkout.defaultRemote=origin in your config."),
argv[0],
dwim_remotes_matched);
return ret;
} else {
if (opts->patch_mode || opts->pathspec.nr)
return checkout_paths(opts, new_branch_info.name);
else
return checkout_branch(opts, &new_branch_info);
}
}
int cmd_checkout(int argc, const char **argv, const char *prefix)

28
t/t2024-checkout-dwim.sh
View file

@ -37,7 +37,9 @@ test_expect_success 'setup' '
git checkout -b foo &&
test_commit a_foo &&
git checkout -b bar &&
test_commit a_bar
test_commit a_bar &&
git checkout -b ambiguous_branch_and_file &&
test_commit a_ambiguous_branch_and_file
) &&
git init repo_b &&
(
@ -46,7 +48,9 @@ test_expect_success 'setup' '
git checkout -b foo &&
test_commit b_foo &&
git checkout -b baz &&
test_commit b_baz
test_commit b_baz &&
git checkout -b ambiguous_branch_and_file &&
test_commit b_ambiguous_branch_and_file
) &&
git remote add repo_a repo_a &&
git remote add repo_b repo_b &&
@ -75,6 +79,26 @@ test_expect_success 'checkout of branch from multiple remotes fails #1' '
test_branch master
'
test_expect_success 'when arg matches multiple remotes, do not fallback to interpreting as pathspec' '
# create a file with name matching remote branch name
git checkout -b t_ambiguous_branch_and_file &&
>ambiguous_branch_and_file &&
git add ambiguous_branch_and_file &&
git commit -m "ambiguous_branch_and_file" &&
# modify file to verify that it will not be touched by checkout
test_when_finished "git checkout -- ambiguous_branch_and_file" &&
echo "file contents" >ambiguous_branch_and_file &&
cp ambiguous_branch_and_file expect &&
test_must_fail git checkout ambiguous_branch_and_file 2>err &&
test_i18ngrep "matched multiple (2) remote tracking branches" err &&
# file must not be altered
test_cmp expect ambiguous_branch_and_file
'
test_expect_success 'checkout of branch from multiple remotes fails with advice' '
git checkout -B master &&
test_might_fail git branch -D foo &&